Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque
h,w = map(int,input().split())
m = ["#"*(w+2)]+["#"+input()+"#" for i in range(h)]+["#"*(w+2)]
temp = [[-1]*(w+2) for i in range(h+2)]
sy,sx = 1,1
temp[sy][sx] = 0
opt = [(1,0),(0,1),(-1,0),(0,-1)]
dq = deque([(sy,sx)])
while dq:
    y,x = dq.popleft()
    for i in opt:
        y1 = y+i[0]
        x1 = x+i[1]
        if m[y1][x1] == "." and temp[y1][x1] == -1:
            temp[y1][x1] = temp[y][x]+1
            dq.append((y1,x1))

cnt = 0
for i in m:
    cnt+=i.count("#")
if temp[h][w] == -1:
    print(-1)
else:
    print((h+2)*(w+2)-cnt-temp[h][w]-1)